Magnetic Quenching of Iodine Fluorescence Excited by a 6328 Å He/Ne Laser

The extent of the magnetic field induced quenching of the fluorescence from the (v′ = 6, J′ = 32) and (v′ = 11, J′ = 128) levels of the ${\mathrm{B\hspace{0.17em}}}^3{\mathrm{\Pi \; (O}}_u^{+})$ state of I₂ has been measured. A He/Ne laser operating at 6328 Å has been used to excite the fluorescence. Combining these measurements with earlier results obtained for the higher vibrational levels allows us to determine the shape of an $O_u^{-}$ repulsive potential energy curve which crosses the B‐state curve. Since the v′ = 6 level is observed to be quenched much more strongly than the levels of higher v′, this $O_u^{-}$ curve crosses the B‐state curve at a low v′ value.